In recent years, it has been tried to provide a new function by accumulating and orienting organic molecules. For example, a block copolymer, in which two or more types of polymers that are incompatible to each other are chemically coupled to each other at their ends, forms a stable microphase-separated structure in its ordered state. In the growth of a microphase-separated structure of a polymer, generally, the structure can grow to some extent by heating the polymer at a temperature that does not destroy the structure of the polymer as a whole. In this method, the domains of microphase-separated structures randomly formed in the polymer serve as cores, and the growth reflecting the respective structures randomly develops. Therefore, in usual, a multi-domain structure in which the microphase-separated structures of each domain are randomly oriented is given. In addition, in the phase-separated structure of a bulk material, a multi-domain structure in which individual domains are disorderly oriented is given. In order to control the orientation of phase-separated structures, as in core generation and growth in a crystallization process, it is necessary to make the phase-separated structures occur at the interface of a membrane and grow inside the membrane while maintaining the orientation.
In order to achieve the above-mentioned object, the present inventors have developed a block copolymer in which a hydrophilic polymer chain and a hydrophobic polymer chain are coupled to each other and developed a microphase-separated structure membrane in which the block copolymer is oriented in the same direction (Patent Document 1). Furthermore, the present inventors have developed a similar microphase-separated structure membrane by using a chalcone analog (Patent Document 2).
On the other hand, in the field of ionics, liquid electrolytes are widely used, and it is the current state that there are still many problems to be solved for providing a wholly solidified element. As already developed solid fuel cells employing ion conductive materials, for example, known are solid oxide fuel cells employing oxides or sulfides of, for example, zirconium, yttrium, bismuth, or vanadium, solid fuel cells employing fused carbonates or phosphoric acid, and solid fuel cells employing fluorine-based polymer electrolyte membranes represented by, for example, Nafion (registered trade mark) and Dow (registered trade mark). Layered porous membranes of polyethylene or polypropylene, polyolefin-based resins, and the like can be thinned and have high porosity and are, from these characteristics, applied to practical use as lithium ion conductive solid electrolytes.
In order to inexpensively produce such an ion conductor at a large scale, microporous structures are required to be reduced in sizes and to be controlled in pore shapes and orientation in the membrane, but the actual state is that these requirements have been still insufficiently achieved.
Furthermore, organic compounds and polymer materials that can be designed to materials having both a soft segment that can accelerate ion movement and a hard segment that can maintain the shape of a solid are being paid attention. Ion conductive mechanisms that utilize a net-like structure of a cross-linked polymer gel, a blend of different polymers, an ionic liquid, or a layer-like structure formed in a membrane surface by, for example, a liquid crystal have been developed. However, it is difficult to control the orientation because of the chemical structures of the materials used, and thereby ion transport anisotropy against an electrode substrate cannot be exhibited (Non-Patent Documents 1 to 3).
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-124088
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 2007-131653
[Non-Patent Document 1] T. Kato, et al., JACS, 126, 994 (2004)
[Non-Patent Document 2] Adam. Z. Weber, et al., J. Electrochem. Soc., 150 (7) A1008 (2003)
[Non-Patent Document 3] T. Kato, et al., JACS, 125, 3196 (2003)
It is an object of the present invention to provide a microphase-separated structure membrane in which an oriented micro-patterned membrane of a polymer thin film showing phase separation in a nanometer region is used, as described in Patent Document 1. The microphase-separated structure membrane has material diffusion characteristics that depend on the orientation of the phase-separated structure in the membrane and can be used as, for example, a photoelectronic functional polymer material, an energy-related material, a surface-modified material, a high-density recording material such as a patterned medium, or a nanofilter. Furthermore, it is an object of the present invention to provide a porous structure that can be used as an anisotropic ion-conductive material such as a fuel cell polymer electrolyte, an ion-exchanging resin, a microreactor thin membrane, a protein-separating membrane, an organic zeolite, or a high orientation template for various pillars.